Christopher Peacocke

It seems to be an obvious truth that There could be something that doesn't actually exist.That is, it seems to be obiously true that ◊∃×).It is sufficient for the truth of that there could be more people, or trees, or cars, than there actually are. It is also sufficient for the truth of that there could be some pepole, or trees, or cars that are distinct from all those that actually exist. Do and suchlike statements involve a commitment to possibilia, to things that possibly exist, but do not actually exist? If not, why not? And if so, what is the nature of the possibilia to which and its ilk commit us? These simple little questions are at the tip of an iceberg.

There are issues in the theory of concepts about which A Study of Concepts could have said more. There are also some issues about which it would have done well to say something different. The commentators in this symposium have successfully identified a series of issues of one or other of these two kinds, and I am very grateful for their thought and detailed attention. I have learned from reflection on their comments, and I take this opportunity to try to carry the discussion forward by addressing a range issues underdeveloped in A Study of Concepts. Georges Rey raises global questions about the project of SoC. Answerability, Quinean challenges and the relations between my approach and covariation or ‘locking’ theories are amongst the problems he raises. The comments of David Papineau are at an intermediate level of generality. He poses questions about the subject-matter of a theory of concepts, and rejects my critique of teleological theories of content. He is also dissatisfied with my account of the relations between actual thought and the normative properties of concepts. I will consider that issue at some length. Jane Heal considers my elaboration of the approach for a specific concept, that of belief. I will take the topics in that order.

A theory of understanding -- Truth's role in understanding -- Critique of justificationist and evidential accounts -- Do pragmatist views avoid this critique? -- A realistic account -- How evidence and truth are related -- Three grades of involvement of truth in theories of understanding -- Anchoring -- Next steps -- Reference and reasons -- The main thesis and its location -- Exposition and four argument-types -- Significance and consequences of the main thesis -- The first person as a case study -- Fully self-conscious thought -- Immunity to error through misidentification relative to the first person -- Can a use of the first-person concept fail to refer? -- Some conceptual roles are distinctive but not fundamental -- Implicit conceptions -- Implicit conceptions : motivation and examples -- Deflationary readings rejected -- The phenomenon of new principles -- Explanation by implicit conceptions -- Rationalist aspects -- Consequences : rationality, justification, understanding -- Transitional -- Applications to mental concepts -- Conceiving of conscious states -- Understanding and identity in other cases -- Constraints on legitimate explanations in terms of identity -- Why is the subjective case different? -- Attractions of the interlocking account -- Tacit knowledge, and externalism about the internal -- Is this the myth of the given? -- Knowledge of others' conscious states -- Communicability : between Frege and Wittgenstein -- Conclusions and significance -- 'Another I' : representing perception and action -- The core rule -- Modal status and its significance -- Comparisons -- The possession-condition and some empirical phenomena -- The model generalized -- Wider issues -- Mental action -- The distinctive features of action-awareness -- The nature and range of mental actions -- The principal hypothesis and its grounds -- The principal hypothesis : distinctions and consequences -- How do we know about our own mental actions? -- Concepts of mental actions and their epistemological significance -- Is this account open to the same objections as perceptual models of introspection? -- Characterizing and unifying schizophrenic experience -- The first person in the self-ascription of action -- Rational agency and action-awareness -- Representing thoughts -- The puzzle -- A proposal -- How the solution treats the constraints that generate the puzzle -- Relation to single-level treatments -- An application : reconciling externalism with distinctive self-knowledge.

This paper presents an account of the understanding of statements involving metaphysical modality, together with dovetailing theories of their truth conditions and epistemology. The account makes modal truth an objective matter, whilst avoiding both Lewisian modal realism and mind-dependent or expressivist treatments of the truth conditions of modal sentences. The theory proceeds by formulating constraints a world-description must meet if it is to represent a genuine possibility. Modal truth is fixed by the totality of the constraints. To understand modal discourse is to have tacit knowledge of the body of information stated in these constraints. Modal knowledge is attained by evaluating modal statements in accordance with the constraints. The question of the general relations between modal truth and knowability is also addressed. The paper includes a discussion of which modal logic is supported by the presented theory of truth conditions for modal statements.

The openness of joint awareness between two or more subjects is a perceptual phenomenon. It involves a certain mutual awareness between the subjects, an awareness that makes reference to that very awareness itself. Properly characterized, such awareness can generate iterated awareness ‘x is aware that y is aware that x is aware...’ to whatever level the subjects can sustain. The openness should not be characterized in terms of Lewis–Schiffer common knowledge, the conditions for which are not met in many basic cases of joint attention. A range of phenomena, including linguistic communication and other interpersonal relations, that have previously been described in terms of common knowledge should rather be seen as involving open joint awareness. An Appendix to this chapter discusses the relations of this approach to Barwise's discussions, and disputes the claim that these mental phenomena require the postulation of self-involving situations.

The topic of Being Known is what I call the Integration Challenge, which is the challenge of providing, for any given domain, a simultaneously acceptable metaphysics and epistemology for that domain. In virtually every domain of thought, it is a substantive task to reconcile our metaphysics and our epistemology of that domain. In some cases, we have an intuitively acceptable metaphysics, but cannot find a plausible epistemology which would allow us knowledge of truths for which that is the right metaphysics. In others, the reverse situation obtains. In yet others, we have an intuitive metaphysics and an intuitive epistemology, but cannot see how they are to be reconciled.

where F is a contradiction (I use his numbering). Tim says about these equivalences: (1) “modulo the implicit recognition of this equivalence, the epistemology of metaphysically modal thinking is a special case of the epistemology of counterfactual thinking. Whoever has what it takes to understand the counterfactual conditional and the elementary logical auxiliaries ~ and F has what it takes to understand possibility and necessity operators.” (158) (2) The idea that we evaluate metaphysically modal claims “by some quite different means [from those we use to evaluate counterfactuals – CP] is highly fanciful, since it indicates a bizarre lack of cognitive economy and has no plausible explanation of where the alternative cognitive resources might come from” (162) (3) “the capacity to handle metaphysical modality is an “accidental” byproduct of the cognitive mechanisms that provide our capacity to handle counterfactual conditionals” (162). The biconditional corresponding to a proposed definition of a concept C may be necessary and a priori. But that leaves open these questions: (1) Does the definition contribute to an explanation of why what are in fact truths containing C are true? (The Explanation Question) (2) Does the definition contribute to an explanation of our knowledge of certain contents containing C? (Epistemic Question) (3) Does the definition contribute to an explanation of our understanding or grasp of contents containing C? (Understanding Question) I argue that applied to (17) and (18), considered as definitions, the answers to these three..

Drawing upon a conception of the metaphysics of conscious states and of first-person content, we can argue that Descartes's transition ‘Cogito ergo sum’ is both sound and one he is entitled to make. We can nevertheless formulate a version of Lichtenberg's objection that can still be raised after Bernard Williams's discussion. I argue that this form of Lichtenberg's revenge can also be undermined. In doing so it helps to compare the metaphysics of subjects, worlds and times. The arguments also apply to Descartes's ‘second Cogito’, that it is one and the same subject that thinks, wills, imagines